Heated roller for control of soil-borne pests such as nematodes, pathogens, fungus, and weeds

Abstract

An apparatus for controlling or eradicating nematodes or other soil-borne pests having a heated metal roller having surface-mounted blades to heat the soil to a desired temperature and depth sufficient to effect control of the relevant species in the soil under the roller. The roller is heated with one or more burners firing across the surface of the roller. The apparatus further includes a heat exchanger through which the combustion products generated by the burner or burners are exhausted and in which the combustion air is preheated. In accordance with one embodiment, the heat exchanger condenses water vapor in the combustion products which water vapor, together with any water that evaporates from the soil during heating, may be captured and returned to the soil.

We claim: 
     
       1. An apparatus for in-situ soil heating comprising:
 a housing having at least one side wall enclosing a space and a top wall adjacent said at least one side wall; 
 a first roller connected with a forward portion of said housing and a second roller connected with a rearward portion of said housing, said rollers together with said at least one side wall providing a substantially air-tight seal around soil undergoing heating; 
 an intermediate roller larger in diameter than said first and second rollers, said intermediate roller comprising a plurality of spaced apart circumferential disk blades; and 
 at least one burner disposed within said forward portion of said housing adapted to provide heat to said intermediate roller. 
 
     
     
       2. The apparatus of  claim 1  further comprising a condensing heat exchanger adapted to receive combustion products produced by said at least one burner and having a combustion air inlet, a condensed water outlet, a cooled combustion products outlet, and a preheated combustion air outlet. 
     
     
       3. The apparatus of  claim 2  further comprising a preheated combustion air conduit providing fluid communication between said preheated combustion air outlet and said at least one burner. 
     
     
       4. The apparatus of  claim 1  further comprising at least one soil return claw disposed within said housing and adapted to remove residual soil from between said circumferential disk blades. 
     
     
       5. The apparatus of  claim 1 , wherein said intermediate roller is a hollow cylinder filled with a thermally conductive fluid. 
     
     
       6. The apparatus of  claim 1  further comprising steam generating means for generating steam. 
     
     
       7. The apparatus of  claim 6  further comprising steam injection means for injecting steam into said soil. 
     
     
       8. The apparatus of  claim 7 , wherein said steam injection means comprises a steam injection plough adapted to receive steam from said steam generating means. 
     
     
       9. The apparatus of  claim 6 , wherein said steam generating means comprises a condensing heat exchanger having a water inlet, a combustion air inlet, a combustion products inlet adapted to receive combustion products generated by said at least one burner, and a steam outlet. 
     
     
       10. The apparatus of  claim 9 , wherein said condensing heat exchanger has a condensed water outlet. 
     
     
       11. The apparatus of  claim 10  further comprising condensed water recycling means for recycling condensed water from said condensed water outlet to said water inlet. 
     
     
       12. The apparatus of  claim 1 , wherein said space is insulated by insulation disposed inside said housing. 
     
     
       13. The apparatus of  claim 1  further comprising mounding means for mounding heated soil. 
     
     
       14. An apparatus for in situ heating of soil comprising:
 a housing having a forward portion and a rearward portion enclosing an area of soil to be heated; 
 a forward roller connected with said forward portion of said housing, a rearward roller connected with said rearward portion of said housing, said rollers and said housing together forming a substantially air-tight cavity over said soil; 
 an intermediate roller having a larger diameter than said forward and rearward rollers connected with said housing intermediate said forward and rearward rollers; 
 a plurality of spaced apart circumferential fins connected with said intermediate roller; 
 at least one burner disposed within said cavity proximate said forward portion of said housing and adapted to direct combustion products generated by said burner onto a circumferential surface of said intermediate roller; and 
 exhaust means for exhausting said combustion products from said cavity. 
 
     
     
       15. The apparatus of  claim 14  further comprising a condensing heat exchanger having a combustion products inlet in fluid communication with said cavity, a condensed water outlet, and a cooled combustion products outlet. 
     
     
       16. The apparatus of  claim 15 , wherein said condensing heat exchanger has a combustion air inlet and a preheated combustion air outlet. 
     
     
       17. The apparatus of  claim 16  further comprising a preheated combustion air conduit disposed within said cavity and providing fluid communication between said preheated combustion air outlet and said at least one burner. 
     
     
       18. The apparatus of  claim 14  further comprising at least one soil return claw disposed within said cavity and adapted to remove residual soil from between said spaced apart circumferential fins. 
     
     
       19. The apparatus of  claim 14 , wherein said intermediate roller is a hollow cylinder filled with a thermally conductive fluid. 
     
     
       20. The apparatus of  claim 14  further comprising steam generating means for generating steam. 
     
     
       21. The apparatus of  claim 20  further comprising steam injection means for injecting steam into said soil. 
     
     
       22. The apparatus of  claim 21 , wherein said steam injection means comprises a steam injection plough adapted to receive steam from said steam generating means. 
     
     
       23. The apparatus of  claim 20 , wherein said steam generating means comprises a condensing heat exchanger having a water inlet, a combustion air inlet, a combustion products inlet adapted to receive combustion products generated by said at least one burner, and a steam outlet. 
     
     
       24. The apparatus of  claim 23  further comprising condensed water recycling means for recycling condensed water produced by said condensing heat exchanger to said water inlet. 
     
     
       25. The apparatus of  claim 14 , wherein said cavity is insulated by insulation disposed inside said housing. 
     
     
       26. The apparatus of  claim 14  further comprising mounding means for mounding heated soil.